The present invention relates to a device serving to support a dispenser of adhesive material. In automatic production machines, for example such as machines used in the manufacture of cigarettes, which operate utilizing strip material consisting typically of a continuous band of paper decoiled from a roll, the need arises periodically for one roll nearing depletion to be replaced with a new roll. The changeover must be effected with no break in continuity of the action by which the strip is fed to the point of use. In effect, a break in feed would translate ultimately into an interruption of the operating cycle of the machine as a whole.
To the end of overcoming this problem, machines of the type in question are equipped with automatic splicing devices capable of making a joint swiftly and faultlessly between the trailing end of a strip decoiling from one roll, near to depletion, and the leading end of a strip drawn from a new roll.
It is usually the case with such splicing devices that the leading end of the new roll of strip will be restrained, motionless, in a position ready to be brought into contact with the trailing end of the depleting roll; thereafter, at the appropriate moment, a splice is effected between the leading and trailing ends by suitable jointing means. Naturally, considerable importance attaches to the speed with which these splicing devices are able to operate; also, a fundamental role is played by the particular jointing means adopted: in effect, the jointing means must guarantee a secure bond during the brief moment when the leading end and trailing end are brought into contact, so that when the new strip is drawn forward by the depleted strip there will be no risk of the two becoming separated.
The jointing means obviously will differ according to the type of strip material utilized; in the case of a paper material, such means consist generally of lengths of adhesive tape, single-sided or double-sided stickers, and often an adhesive material of liquid or paste consistency directed to the point of use and applied in a convenient manner by suitable dispensing means. The use of stickers or lengths of adhesive tape dictates that the area of the bond between the leading end of the new strip and the trailing end of the depleted strip will be only of modest proportions, limited generally to a central part of the strips as considered in the transverse dimension. This can occasion an incorrect mutual alignment of the joined ends at the moment when the new strip is drawn forward by the depleted strip; with the lateral portions of the leading end of the new strip remaining unstuck, moreover, these same portions can fold back and inhibit the correct feed motion of the strip.
By contrast, the use of a liquid or paste adhesive affords the advantage of allowing a new strip and a depleting strip to be bonded together across the full width of the strip material, and thus avoiding drawbacks of the type in question. The glue must, however, be applied across the entire transverse dimension of the strip, swiftly and with precision. Known means for dispensing such adhesive materials are substantially of two types. In a first type, use is made of one or more nozzles connected via rigid or flexible small bore tubes to tanks containing the adhesive material.
A second type makes use of gumming rollers, which are dipped initially in the adhesive material and then positioned and rotated in such a manner as to coat a portion of the leading end of the new strip. The problems betrayed by these types of dispensers become evident whenever there is a need, as already intimated, for the adhesive material to be applied precisely, at high speed, and spread over areas of notable dimensions.
With this in mind, one may consider the requirement for precision and speed when the adhesive material in use is a fast-bonding type. Where a changeover of rolls is to be effected, the adhesive material must be applied to a relatively long portion of the strip, typically of a length substantially equivalent to the transverse dimension of the selfsame strip, and where the dispenser is installed, for example, in a machine for fashioning cigarette packets or multipack cartons, applied substantially along the full longitudinal dimension of the securing flaps exhibited by the corresponding cardboard die-cuts.
It is clear, therefore, that the problems involved in moving these nozzles and the respective feed tubes at a high velocity are not inconsiderable, given the inertia of the moving parts; and equally clear in the case of the rollers, moreover, that a clean and accurate gumming action becomes difficult to achieve, once certain operating speeds are exceeded.
Similarly evident is the limited flexibility of use afforded by such dispensers, which certainly are not able to respond to the different requirements typically encountered in manufacturing machines of the type in question.